Article Prepared By Robert Michie
NMTC, Lee District
Last Reviewed: 17 February 2004

Update/Resolution:

VDOT rendered the pedestrian underpass safe in December 2004 by removing
the concrete shards shown in Photos 1 and 2.

Summary:

In the early 1990's, Fairfax County built a pedestrian tunnel underneath
the northbound I-495 slip ramp at South Van Dorn Street (see Tax Map 81-2).
Ten years later, parts of the concrete framing of the tunnel are showing
signs of wear and tear. This tunnel is identified as Structure #5018.

Exhibit 1: Map of Subject Area

Discussion:

Exposure to weather over ten years as well as vibration from traffic has
cracked the concrete framing around the tunnel entrance. Although it is
doubtful if the stability of the tunnel structure itself is in question, a
concrete shard on the right side of the South entrance is going to fall
soon. A better view of this crack is in Photo 2. In a worst-case scenario,
it could hit a pedestrian.

The North entrance has another problem. Although on side of the tunnel
frame shows the same stress cracks as on the south side, the retaining walls
flanking the entrance show signs of leaning outward. The differences between
the top and the bottom of the wall on the right side of the North entrance,
for example, shows a lean of about 4 cm (1.5 inches).

Field Check 26 October 2004

Photo 2:
South side of Tunnel , right side as shown in Photo 1. This crack is
sixteen feet long, and it is mostly separated from the frame and the
retaining wall to its right.

It represents a hazard to pedestrians as that it can fall at any
time, as the missing piece on the left side of Photo 1 illustrates.
This, however, will be a concrete shard twice as long as the missing
piece in Photo 1.

Photo 3:
North side of the Pedestrian Tunnel, retaining wall on the right as you
face the entrance. Note the apparent outward tilt of the wall, using the
tunnel framing as a guide. The wall is leaning out about 4 cm ( about
1.5 inches) at the top of the frame when compared to the bottom of the
frame.

The retaining wall on the left side of the North entrance shows
the same outward tilt. Note the Structure number (5018) that appears
near the centerline of the photograph.